Methods for controlling an output of an AC voltage are used in particular in dimmers for controlling the brightness of lamps. Known methods for controlling the output are the phase trailing-edge control and phase leading-edge control, for example. With the phase leading-edge control, a current flow delayed after the zero crossing of the AC voltage is switched on. With the phase trailing-edge control, the current flow is already switched off prior to the zero crossing of the AC voltage.
In case of capacitively coupled loads, methods of this type have the disadvantage, that the switching-on procedures of the current flows result in large voltage differences, in particular to a change in the sign of the voltage at the capacitors. The large voltage differences lead to undesired current pulses, which cause disruptions, and can damage components. In particular, these methods are not suitable for dimming LED lamps when the LED lamps are connected to an AC voltage network via a rectifier and a coupling capacitor. So far, such LED lamps have been regarded as not dimmable.